Grasping is fundamental to activities of daily living (ADL) and is usually impaired following stroke and traumatic brain injury. In the absence of grasping, the impaired arm tends to be neglected, retarding its recovery; accordingly, grasp training is a high priority for rehabilitation of the upper limb.
Repetitive training tasks are often difficult for brain injured individuals, due not only to their motor deficits, but also to their tactile and proprioceptive deficits. Although there are reports in the literature of inconclusive evidence, many studies many studies have documented the efficacy of EMG biofeedback. For example, a group of hemiplegic patients who were given occupational therapy plus EMG-biofeedback improved their upper limb function relative to a control group receiving only occupational therapy]. Biofeedback from the EMGs of the extensor carpi radialis and extensor digitorum communis improved the wrist and finger extension of stroke subjects. EMG biofeedback has even been proposed as a therapy for remotely supervising home users. The method, however, remains a challenge, as EMG requires expertise and is difficult for self-application and interpretation. A more fundamental problem of using EMG for biofeedback is that electrical activities of muscle vary considerably from one repetition to the next, even when the underlying movement is kinematically consistent.